Non-stalling gasoline motor fuels



United States Patent Delaware No Drawing. Filed May 28, 1959, Ser. No. 816,304

8 Claims. (Cl. 4463) This invention relates to gasoline fuel compositions, and more particularly to gasoline fuel compositions that have reduced engine stalling tendencies at cool, humid atmospheric conditions.

When an internal combustion engine is operated at cool, humid atmospheric conditions, using a gasoline fuel having a relatively low 50 percent ASTM distillation point, i.e., below about 235 F, excessive engine stalling is apt to be encountered at idling speeds during the warmup period, especially where engine idling occurs following a period of light load operation. Engine stalling under such conditions has been attributed to the partial or complete blocking of the narrow air passage that exists between the carburetor throat and the carburetor throttle valve during engine idling, by ice particles that deposit upon and adhere to the metal surfaces of the carburetor parts. Such icing of carburetor parts occurs as a result of the condensation of moisture from the air drawn into the carburetor and as a result of the solidification of such condensed moisture. The aforesaid condensation and solidification of moisture are caused by the refrigerating effect of rapidly evaporating gasoline. Accordingly, excessive engine stalling due to carburetor icing occurs as a practical matter only in the instance of gasolines containing a large proportion of relatively highly volatile components. In practice, the problem of engine stalling due to carburetor icing has been found to be serious, under cool, humid atmospheric conditions, in connection with gasolines having a 50 percent ASTM distillation point not greater than about 220 F.

Excessive engine stalling is, of course, a source of annoyance owing to the resulting increased fuel comsumption, battery wear and inconvenience of frequent restarting. It is therefore important that the inherent engine stalling characteristics of gasoline fuels be reduced substantially, where the 50 percent ASTM distillation point of such gasoline fuels is suliiciently low to cause a problem in this respect.

The present invention relates to gasoline fuel compositions that comprise hydrocarbon mixtures boiling in the gasoline range and that normally tend to promote engine stalling by carburetor icing, which fuel compositions exhibit reduced engine stalling tendencies, and which are thereby rendered more suitable for use as motor fuels. We have found that such improved gasoline compositions can be obtained by incorporating therein a small amount of a quaternary l,l,2-substituted imidazolinium salt, one of whose 1-substituents is a lower aliphatic group that contains not more than six carbon atoms and preferably two to four carbon atoms, and that contains only atoms selected from the group consisting of carbon, hydrogen and oxygen. The other l-substi-tuent of the l,l,2-substituted imidazolinium salts that are useful for the purposes of this invention is selected from the group consisting of rnonovalent hydrocarbon and halohydrocarbon radicals containing 1 to 10 and preferably 2 to 7 carbon atoms. The Z-substituent of the 1,1,2-substituted imidazclinium salts whose use is included by this invention is an aliphatic hydrocarbon radical containing 11 to 17 carbon atoms, especially 13 to 17 carbon atoms, and this substituent can be saturated or unsaturated and straight or branched-chain. The anionic substituent of the quaternary 1,1,2-substituted imidazolinium salts whose use is included by this invention is an acid-forming anion. An example of an especially effective lower aliphatic l-substituent for the purposes of this invention is the ethylol, i.e., Z-hydroxyethyl group, but salts containing other 1- substituents, such as propylol or butylol can be used. Examples of other open-chain lower aliphatic groups of the type indicated are methyl, ethyl, propyl, and butyl. Especially good results are obtained when the other 1- substituent is an aralkyl radical containing 7 to 10 carbon atoms, such as the benzyl radical. However, effective results are also obtained when such other l-substituent is an aliphatic group such as chlorobutyl. Examples of other monovalent hydrocarbon and halohydrocarbon radicals of the class indicated are methyl, butyl, monochlorophenyl, chloropropyl and chloroethyl. Outstanding results have been obtained when the Z-substituent is heptadecenyl or a mixture of heptadecenyl or heptadecadienyl radicals. However, an appreciable improvement is obtainable when the Z-Substituent is as low as n-undecyl. Examples of other 2-substituents within the class disclosed are n-tridecyl, n-pentadecyl, and n-heptadecyl. Exceptionally good results are obtained when the anionic substituen-t is a strong acid-forming anion such as the chloride ion. However, salts containing other acid-forming anions such as bromide or iodide can be used. Examples of especially eifective quaternary 1,1,2-substituted imidazolinium salts for the purposes of the present invention are l-benzyLI-(Z-hydroxyethyl) 2 heptadecenylimidazolinum chloride and l-benzyl 1 (2-hydroxyethyl)-2- heptadecadienylimidazoliniurn chloride. An example of another effective 1,1,2-substituted imidazolinium salt is 1- (4-chlorobutyl) 1 (Z-hydroxyethyl)-2-heptadecenylimidazolinium chloride. Examples of other quaternary 1,1,2-substituted imidazolinium salts included by the present invention are l-methyl 1 (2-hydroxypropyl)-2- undecylimidazolinium bromide and the 1-2-methylbenzyl- 1-(2-l'iydroxyethyl) 2 tridecylimidazolinium chloride. The quarternary 1,1,2-substituted imidazolinium salts disclosed herein need not be pure, and can contain, for example, minor proportions of quaternary 1,2,3-substituted imidazolinium salts where the 3-substituent is the same as, and in lieu of, the second-mentioned l-substituent, without greatly reducing the nonstalling properties of the gasoline composition of this invention. The invention is important in connection with gasolines having a 50 percent ASTM distillation point not greater than about 220 F., as such gasolines normally involve a severe engine stalling problem under cool, humid atmospheric conditions.

The quaternaryl,1,2-substituted imidazoliniurn salts whose use is included by this invention are cation-active, polar, surface active materials. While the invention is not limited to any theory of operation it might appear that the addition agents disclosed herein, by virtue of their polarity, tend to orient themselves upon the metal surfaces of the throttle valve and other critical carburetor parts contacted by the gasoline compositions, thus forming a moisture-displacing residual coating upon said carburetor parts that tends to prevent the adherence to said metal surfaces of accumulations of ice of such magnitude as to block the narrow air passages that exist in a carburetor throat at engine idling conditions. It is also considered possible that the addition agents disclosed herein may tend to orient themselves about small ice: particles, thus tending to prevent the formation of macrocrystals of ice of a size suflicient to block carburetor air passages at engine idling conditions. Although the effectiveness of the herein disclosed addition agents is believedv to be at tributable in some way to the particular polar, surface active characteristics thereof, this general explanation is more or less negatived by the fact that many other sur- 3 face active agents have little or no effect upon the carburetor icing tendencies of gasolines.

The preparation of the quaternary 1,l,2-substituted imidazolinium salts whose use is included by this invention is conventional and forms no part of the present invention. In fact, several of the salts disclosed herein are commercially obtainable. When this is not the case, the quaternary salts are easily prepared in conventional fashion, for example, by reaction of a suitable hydrocarbon halide with the desired 1,2-substituted imidazoline. In accordance with this preparation, the anionic substituent of the salt will be a halide radical. However, it will be understood that the halide ion can be converted by metathesis or ion-exchange in conventional manner. For example, the halide ion can be converted to sulfate, phosphate, sulfonate, alkyl sulfate, dialkyl phosphate, and the like.

The addition agents disclosed herein are useful when incorporated in gasoline compositions of the type disclosed in an amount sufficient to reduce the engine stalling characteristics thereof. For example, some improvement in the stalling characteristics of gasolines of the type disclosed herein can be obtained by addition thereto of the most eifective addition agents of the class disclosed herein in proportions as small as about five pounds of agent per 1,000 barrels of gasoline, but preferably the agents disclosed herein are employed in proportions of at least as great as 7.5 pounds per 1,000 barrels of gasoline. Normally, a marked improvement in the stalling characteristics of gasolines will be obtained by the incorporation therein of the most effective addition agents disclosed herein in proportions in the range of about 7.5 to 100 pounds per thousand barrels of gasoline. In instances of less effective addition agents of the class disclosed herein it may be necessary to employ the agents in proportions up to or in excess of 250 pounds per thousand barrels of gasoline, but substantially greater proportions will normally produce no significant additional improvement in the stalling characteristics of the gasoline. In no instance should the addition agents disclosed herein be added to gasoline in amounts such as to produce an undue adverse effect on the volatility, combustibility, antiknock or guinforming characteristics of the gasoline.

It will be appreciated that the optimum proportion of the antistalling addition agents disclosed herein can vary within the range indicated above in accordance with the particular gasoline employed, inasmuch as the problem of engine stalling due to carburetor icing is a function of the 50 percent ASTM distillation point of the gasoline. Thus, greater concentrations of the antistalling addition agents are normally desirable with decreasing 50 percent ASTM distillation points. The optimum concentration of the antistalling addition agents disclosed herein, may also vary somewhat in accordance with the particular make and model of engine in which the gasoline is used, as well as in accordance with the severity of the atmospheric conditions encountered. With regard to this lastmentioned factor, the problem of engine stalling due to carburetor icing resulting from the refrigerating effect of evaporating gasoline upon moisture condensed from the atmosphere has been found to be serious at low temperatures, e.g., 35, 40, 45, 50 F., and when the relative humidity is in excess of about 55 percent, e.g., 75 percent, and 99 percent. The optimum proportion of the antistalling addition agents disclosed herein, in any given case, will be sufficient to eifect substantial reduction in the stalling tendencies of the fuel at the particular atmospheric conditions of temperature and humidity which are likely to be encountered in service.

Practically speaking, the problem of engine stalling due to carburetor icing caused by rapid evaporation of gasoline occurs only in connection with gasolines having a 50 percent ASTM distillation point less than 235 F. While occasional engine stalling may occur as a result of carburetor icing at sever atmospheric conditions of temperature and humidity with gasolines having somewhat higher 50 percent ASTM distillation points, experience has indicated that the problem does not assume major importance except with gasolines of the character indicated. As indicated, the problem of engine stalling due to carburetor icing is especially sever in connection with gasolines having a 50 percent ASTM distillation point of less than about 220 F. The invention is important in connection with such gasolines. The term gasoline is used herein in its conventional sense to include hydrocarbon mixtures having a percent ASTM distillation point of not more than about 392 F. and a 10 percent ASTM distillation point of not more than 140 F, as defined in ASTM specification D 439.

The antistalling addition agents whose use is included by this invention can be incorporated in the base gasoline fuel compositions in any suitable manner. Thus, they can be added as such to gasoline or they can be added in the form of dispersions or solutions in solvents such as butanol, isopropanol, ethanol, methanol, benzene, toluene, heptane, kerosene, gasoline, mineral lubricating oil, or the like, which solvents may or may not themselves contribute to the antistalling characteristics of the gasoline motor fuel composition. If desired, the herein disclosed antistalling addition agents can be incorporated in gasoline fuel compositions in admixture with other materials designed to improve one or more properties of the gasoline, such as antioxidants, antigumming agents, e.g., 2,6- ditertiary-butyl-4-methylphenol, antiknock agents, e.g., tetraethyl lead, lead scavenging agents, e.g., ethylene dibromide, ethylene dichloride, corrosion inhibitors, e.g., oil-soluble dialkyl amine phosphates, dyes, and the like.

It is emphasized that the 1,1,2-substituted imidazolinium chlorides disclosed herein are quaternary ammonium salts, which are not to be confused with the addition salt-s normally formed by the reaction of amines and acids. Unlike the corresponding addition salts, the quaternary salts disclosed herein contain a pentavalent nitrogen atom. As is well-known the pentavalent nitrogen atom of quaternary ammonium compounds sharply differentiates these compounds from ammonium addition salts from a chemical standpoint. For example, quaternary ammonium bases exhibit basicity comparable to that of a strong base such as an alkali metal hydroxide, whereas the corresponding nonquaternized amines are relatively weak bases. Also, amine addition salts are decomposed to form free amines when treated with a strong base like sodium hydroxide. In contrast, quaternary ammonium salts do not release free amines when reacted with sodium hydroxide in aqueous solution. Other important differences also exist.

The utility of the gasoline motor fuel compositions of this invention has been demonstrated by two different test procedures. In the one test, referred to hereinafter as the mock fuel system test, test fuel at an initial temperature of about 50 F. and air at ambient temperature and having a relatively humidity of about 90 percent are introduced at the respective rates of 0.22 mL/sec. and 130 mL/sec. through a 0.25 in. 1D. brass tube into the upper portion of a glass icing chamber consisting of an inverted l in. x 8 in. test tube, the interior of which is maintained at an absolute pressure of 6 in. Hg by means of a reduced pressure exhaust conduit connected to the base of said icing chamber. Performance of a test fuel is determined by comparing the time for ice formation on the brass tube with that required for the uninhibited fuel under the same test conditions. Test results are expressed in terms of the isopropanol (a common commercial antistalling agent) concentration required in the uninhibited fuel to obtain the same anti-icing action. Each test run requires approximately three minutes.

In carrying out the tests according to the above-described procedure, a number of test gasoline samples were made up in the respective proportions of 50 and pounds per 1,000 barrels of base gasoline of 60 weight percent solutions in isopropanol of each of (I) mixed 1-benzyl-1-(Z-hydroxyethyl)-2-heptadecenyl imidazolinium chloride, 1-benzyl-1-(2-hydroxyethyl)-2-heptadecadienylimidazolinium chloride, hereinafter referred to as compound 1, (II) l-benzyl-l-(2-hydroxyethyl)-2-heptadecenylimidazolinium chloride, hereinafter referred to as compound 2, (III) mixed 1,1,2-substituted imidazolinium chlorides wherein one of the l-substituents is 4- chlorobutyl, the other is Z-hyd-roxyethyl, and the 2-substituent is a mixture of mixed n-C I1-C13, n'C and n-C 'alkyl radicals, but chiefly the n-C alkyl radical, hereinafter referred to as compound 3 and (IV) 1-(4- chlorobutyl) -1(2-hydroxyethyl) -2-heptadecenyl-imidazolinium chloride, hereinafter referred to as compound 4. Compound 1 was a commercial material containing a minor proportion of 1-(2-hydroxyethyl)-2-heptadecenyl- 3-benzylimidazolinium chloride and 1-(2-hydroxyethyl)- 2-heptadeoadienyl-3-benzylimidazolinium chloride. Compound 2 Was a commercial mixture containing a minor proportion of 1-(2-hydroxyethyl)-2-heptadecenyl-3-benzylimidazolinium chloride. Compound 3 was a commercial mixture containing a minor proportion of 1-(2-hydroxyethyl)-2-C alkyl-3-(As'ohlorobutyl) imtidazclinium chloride. Compound 4 was a commercial mixture containing a minor proportion of 1-(2-hydroxyethyl)-2- heptadecenyl-3(4-chlorobutyl) imidazolinium chloride. The base gasoline employed in the above-indicated tests, hereinafter referred to as test gasoline A, was a motor grade gasoline having the following characteristics:

Knock rating research method, O.N. 95.0 TEL, mL/gal. t 2.0 Vapor pressure, Reid, lb 8.0 Distillation, gasoline:

Over point, F. 98 End point, F. 355 evap. at, F. 130 50% evap. at, F. 200 90% evap. at, F. 280

The results obtained in the above-described tests are presented in the following table:

Table 4 II III IV Test Sample Make-Up:

Test Gasoline A, Vol. Percent Addition Agents, Lbs/1000 Bbls. (Active Agent):

Compound 1 Compound 2-- Compound 3.- Compound 4 Inspection: Mock Fuel System Test isopropanol Equivalent, Vol. Percent As will be seen from the foregoing results, compounds 1, 2, 3 and 4 each reduced the icing tendencies of the test gasoline, compounds 1 and 2 being especially outstanding in this respect.

According to the other test procedure employed, hereinafter referred to as the road-load, cold-room engine test, a 216 cubic-inch Chevrolet engine employing a standard, Carter down-draft carburetor and equipped with a Power- Glide transmission is operated under a dynamometer load amounting to 15 horsepower on a test stand under cycling conditions in a cold room maintained at 40 F. for a warm-up period of 20 cycles. Each cycle comprises 40 seconds at 2,000 rpm. followed by an idle for 20 seconds at 450 rpm. Air is supplied to the carburetor at ambient temperature and pressure conditions and at 96 percent relative humidity. The number of engine stalls is observed and reported as stalls per 20 cycles. In the present instance, results were also reported in terms of equivalent gasoline volatility performance and in terms of isopropanol equivalent.

In carrying out this test procedure, test gasoline samples were made up containing 15 pounds per thousand barrels of base gasoline of a 60 Weight percent solution of compound 2 in isopropanol. The base gasoline employed in this test, hereinafter referred to as test gasoline B, was a compounded motor grade gasoline containing a commercial organic phosphate rust inhibitor in the proportion of 16 pounds per thousand barrels, 0.5 volume percent of a 100 SUS/ 100 F., lubricating distillate oil, 1 ml./gal. tetraethyl lead, and 0.3 theory of a commercial preignition suppression addition agent, based on a tetraethyl lead content of 3 ml./gal., said compounded gasoline having the following characteristics:

Vapor pressure, Reid, lbs 8.5

Distillation, ASTM Over point, F 100 End point, F. 357 10% evap. at, F. 136 50% evap. at, F 200 evap. at, F. 277

The result obtained in the above-described test are set forth in the following table:

From the results presented in Tabel B above it will be seen that compound 2 when employed in the base gaso line in proportions of 9 pounds of the compound per 1,000 barrels of gasoline reduced the number of stalls during a 20 cycle warm-up period from an average of 19.5 to an average of 9.5, a reduction of more than 50 percent. Stated another way, the stalling characteristics of the base gasoline that as such had a 50 percent ASTM distillation point of 200 F. were reduced by compound 2 in the proportion of 9 pounds per 1,000 barrels of gasoline so that the stalling characteristics of the resulting gasoline were equivalent to those of an uninhibited base gasoline having a 50 percent ASTM distillation point of 229 F. Stated in still another way, the incorporation in the base fuel of compound 2 in the proportion of 9 pounds per 1,000 barrels of gasoline reduced the stalling characteristics of the base gasoline by the same amount as 1.25 volume percent isopropanol. Moreover, it has been found that the above-indicated beneficial results are obtained without significant reduction of the octane number of the fuel, without increasing the emulsion-forming tendencies of the base gasoline, without increasing the copper corrosivity of the gasoline, and without significantly increasing the existent gum content and the copper dish gum-forming tendencies of the base gasoline. In addition, a gasoline containing compound 2 in the proportion of 15 pounds per thousand barrels of gasoline was found to impart good rust inhibiting characteristics to the base gasoline.

While the addition agents employed in the above-indicated specific embodiments are especially eifective for the purposes of this invention, it will be understood that the invention is not limited to these specific agents inasmuch as all of the agents disclosed herein are cation-active, surface-active agents, and inasmuch as the cationic radicals that characterize such addition agents prossess a similar balance of hydrophilic and hydrophobic properties. Accordingly, other addition agents of the class described herein can be substituted for those indicated in the preceding embodiments in the same or equivalent proportions with good results.

To the gasoline fuel compositions of the present invention there can be added one or more additional agents designed to improve one or more characteristics of the gasoline fuel. For example, antioxidants, antiknock agents, ignition control additives, other deicing agents, antirust agents, dyes, lead scavenging agents and the like can be added to the gasoline compositions of this inven tion, and the invention specifically includes gasoline compositions containing such additives.

Numerous additional modifications of the invention will readily suggest themselves to those skilled in the art, and resort can be had to such modifications without departing from the spirit or scope of the invention. Accordingly, only such limitations should be imposed on the invention as are indicated in the claims appended hereto.

We claim:

1. A gasoline motor fuel composition comprising a major amount of a hydrocarbon mixture boiling in the gasoline range, that has a 50 percent AST M distillation point not greater than 220' F. and that normally tends to promote stalling of internal combustion engines by carburetor icing, and containing a small amount, suflicient to reduce the carburetor icing characteristics of the composition, of a quaternary 1,1,2-substituted imidazolinium salt, one of whose l-substituents is a lower aliphatic group containing not more than six carbon atoms and that contains only atoms selected from the group consisting of carbon, hydrogen, and oxygen, and the other of whose l-substituents is selected from the group consisting of monovalent hydrocarbon and halohydrocarbon radicals containing 1 to 10 carbon atoms, whose 2-substituent is an aliphatic hydrocarbon radical containing 11 to 17 carbon atoms, and whose anionic substituent is an acid-forming radical selected from the group consisting of halide, sulfate, phosphate, and sulfonate radicals.

2. The composition of claim 1 wherein said small amount is about 5 to 250 pounds per thousand barrels of said hydrocarbon mixture.

3. The composition of claim 1 where said small amount is about 7.5 to 100 pounds of said salt per thousand barrels of said hydrocarbon mixture.

4. A gasoline motor fuel composition comprising a major amount of a hydrocarbon mixture boiling in the gasoline range, that has a 50* percent ASTM distillation point not greater than 220 F. and that normally tends to promote stalling of internal combustion engines by carburetor icing, and containing a small amount, sufiicient to reduce the engine stalling characteristics of the composition, of a quaternary 1,1,2-substituted imidazolinium salt, one of whose l-substituents is an alkylol group containing 2 to 4 carbon atoms, the other of whose l-substituents is selected from the group consisting of aralkyl radicals containing 7 to 10 carbon atoms, and haloalkyl radicals containing 2 to 6 carbon atoms, and whose 2-subs-tituent is an aliphatic hydrocarbon radical containing 13 to 17 carbon atoms, and whose anionic substituent is a halide radical.

5. The composition of claim 4 where said salt is one having as one of its l-substituents a benzyl group and as the other of its l-substituents an ethylol group, and as its 2-substituent a mixture of heptadecenyl and heptadecadienyl radicals.

6. The composition of claim 4 where said salt is 1- benzyl-l-ethylol-2-heptadecenylimidazolinium chloride.

7. The composition of claim 4 where said salt is one having as one of its l-substituents a 4-chlorobutyl radical and as the other of its l-substituents an ethylol radical, and as its 2-substituent a mixture of alkyl radicals containing 11 to 17 carbon atoms.

8. The composition of claim 4 where said salt is 1- (4-chlorobutyl) 1 ethylol-2-heptadecenylimidazolinium chloride.

References Cited in the file of this patent UNITED STATES PATENTS 2,579,692 Neudeck Dec. 25, 1951 2,622,018 White et al. Dec. 16, 1952 2,773,879 Sterlin Dec. 11, 1956 2,839,371 Sigworth et al. June 17, 1958 2,863,742 Cantrell et al Dec. 9, 1958 2,872,303 Donlan Feb. 3, 1959 2,875,210 Bcllenbeck et al Feb. 24, 1959 2,886,423 Vitalis et al May 12, 1959 2,888,400 Green May 26, 1959 2,907,646 OKelly et al Oct. 6, 1959 2,915,528 Raifsnider Dec. 1, 1959 OTHER REFERENCES Petroleum Refining with Chemicals, Kalichevsky and Kobe, Elsevier Pub. Co., 1956, p. 480. 

1. A GASOLINE MOTOR FUEL COMPOSITON COMPRISING A MAJOR AMOUNT OF A HYDROCARBON MIXTURE BOILING IN THE GASOLINE RANGE, THAT HAS A 50 PERCENT ASTM DISTILLATION POINT NOT GREATER THAN 220*F. AND THAT NORMALLY TENDS TO PROMOTE STALLING OF INTERNAL COMBUSTGION ENGINES BY CARBURETOR ICING, AND CONTAINING A SMALL AMOUNT, SUFFICIENT TO REDUCE THE CARBURETOR ICING CHARACTERISTICS OF THE COMPOSITION, OF A QUATERNARY 1,1,5-SUBSTITUTED IMIDAZOLINIUM SALT, ONE OF WHOSE 1-SUBSTITUENTS IS A LOWER ALIPHATIC GROUP CONTAINING NOT MORE THAN SIX CARBON ATOMS AND THAT CONTAINS ONLY ATOMS SELECTED FROM THE GROUP CONSISTING OF CARBON, HYDROGEN, AND OXYGEN, AND THE OTHER OF WHOSE 1-SUBSTITUENTS IS SELECTED FROM THE GROUP CONSISTING OF MONOVALENT HYDROCARBON AND HALOHYDROCARBON RADICALS CONTAINING 1 TO 10 CARBON ATOMS, WHOSE 2-SUBSTITUENT IS AN ALIPHATIC HYDROCARBON RADICAL CONTAINING 11 TO 17 CARBON ATOMS, AND WHOSE ANIONIC SUBSTITUENT IS AN ACID-FORMING RADICAL SELECTED FROM THE GROUP CONSISTING OF HALIDE, SULFATE, PHOSPHATE, AND SULFONATE RADICALS. 